论文部分内容阅读
本文研究了1976年11月7日、12月13日宁蒗—盐源6.7级和6.4级地震前,震中周围150公里范围内的小震活动。发现震前从1973年底开始的两年多时间内,M_L~*≥3.0级地震围成空区,震前4个月,震源区附近小震活动加强,致使空区消失,最后在空区的一端发生主震。同时还伴随有M_L≥2.3级地震的月频度由高值——低值——再回升到高值;b值由低值到高值;月应变释放速率震前呈明显的加速及Σ(t)值出现高值等异常现象。文中用突起点模式的思路对上述异常特征作了解释。
This paper studies the small earthquakes within 150 kilometers around the epicenter before and on November 7, 1976 and December 13, 1976 before the Ninglang-Yanyuan 6.7 and 6.4 earthquakes. It is found that the M_L ~ * ≥3.0 earthquakes formed an empty area within two years from the end of 1973 before the earthquake. During the first 4 months before the earthquake, the small earthquakes in the vicinity of the focal area intensified, resulting in the disappearance of the vacant area. Finally, The main shock occurred at one end. At the same time, the frequency of M_L≥2.3 earthquakes also rose from high value to low value to high value again. The value of b was from low value to high value. The monthly strain release rate was obviously accelerated before earthquake and Σ ( t) values appear abnormal and so on. In this paper, the protruding point mode of thinking of the above anomalies were explained.